Method for shaping honeycomb core

ABSTRACT

A method of shaping a layer of settable material such as honeycomb core (24) including placing the core on a flexible support (38); translating the flexible support (38) and core into an oven (28); heating the core to a desired forming temperature in the oven; translating the flexible support (38) and core (24) horizontally from the oven into a forming area (26); lowering a contoured upper die (32) onto the core (24); tensioning the flexible support (38); pressing the core between the tensioned flexible support and the upper die so that the core (24) is forced to conform to the shape of the die (32); cooling the core to set temperature; and raising the die (32) to remove the finished shaped core, is provided. Additionally, a shaping apparatus (22) located in a forming area (26) adjacent an oven (28), for shaping a settable material such as honeycomb core (24) is provided, including: an upper die (32); first and second tensioning assemblies (70), (72) each including a torque supply system; first and second guide assemblies (50), (52) for translating the tensioning assemblies into and out of the oven (28); at least one flexible support (38) wrapped around and between the tensioning assemblies (70), (72) upon which the core may be placed; a regulation system for equalizing tension about the core during pressing; and optional support rollers (166) for focusing the flexible support (38) against the upper die (32) during pressing. A tensioning assembly including a roller (76) and a torque supply system having an air motor (84), is provided. Alternatively, a tensioning assembly including a number of short rollers (92) each powered by a torque supply system having an air motor (108); and a like number of tensioning sub-assemblies (90) each having multiple flexible belts (96) attached thereto, is provided.

This is a divisional of the prior application Ser. No. 08/545,190, filedOct. 16, 1995, now U.S. Pat. No. 5,780,074, the benefit of the filingdate of which is hereby claimed under 35 U.S.C. §120.

FIELD OF THE INVENTION

The present invention relates to methods and apparatus for shapingsettable materials, and more particularly to a method and apparatus forshaping flat honeycomb core into a predetermined contour shape.

BACKGROUND OF THE INVENTION

The current method of shaping honeycomb core includes placing the coreon a series of horizontal support rods and sliding the combination intoan oven. The core is heated to its forming temperature, i.e., theparticular temperature at which the core becomes shapable. Once the coreis properly heated, the support rods and core are removed from the ovenand the rods are retracted laterally to either side. This causes thecore to fall loosely onto a lower die. There, a worker correctly alignsthe core relative to the die. Next, the heated core is pressed for aperiod of time between the lower die and an upper die that is shaped inthe reverse-image of the lower die (i.e., male/female die pair). Afterpressing the hot core, the dies continue to hold the core until it coolsto a set temperature. Once set, the dies recede, and the shaping processis complete.

There are a number of disadvantages associated with the current method.A first disadvantage involves the forming temperature. The core must beheated to a particular temperature in order to bring it to a malleablestate. The time spent retracting the rods and placing the core on thelower die allows the core to cool. A transfer of the core heat to thelower die begins when the core is transferred to the lower die. Thesesteps lower the initial core temperature and must be accounted for byincreasing the oven temperature to compensate for the anticipated heatloss and by requiring the worker to accurately position the core on thelower die in a short period of time. Both are disadvantageous: increasedheat requires more energy and less temperature precision, shortplacement time decreases accuracy. Even if the initial temperature ofthe core is correctly adjusted, the forming temperature is adverselyaffected because the lower die continues to absorb heat from the core.This reduces the amount of time available for pressing the core atrequired forming temperature.

A second disadvantage with the current method involves cooling time.After the core has been pressed at its proper forming temperature forthe required amount of time, the core must be allowed to cool to aparticular temperature while being held at its new shape. If the core isreleased prior to reaching this temperature, it will tend to return(i.e., spring back) toward its original shape. This cool down period islonger than desired when using the current method due to the slow rateof heat dissipation from the dies.

A third disadvantage of the current method is the requirement for aworker to accurately position the hot core on the lower die prior topressing. Human aligning is often imprecise, and typically worsens intime critical activities.

Prior art attempts to solve the above disadvantages have beenunsuccessful. U.S. Pat. No. 5,084,226 describes a method of shaping asheet of thermoplastic material by placing the material on a flexiblesupport and heating the material and the support in an oven. Tension isapplied to the support to force it to remain substantially horizontalduring heating. Once removed from the oven, tension on the support isrelaxed. This allows the material and support to drop into a lowerfemale former (i.e., a female die), where the weight of the materialitself forces the material to adopt the shape of the female die. Thismethod is inadequate for shaping honeycomb core, because the weight ofhoneycomb core is insufficient to force the core to permanently adoptthe shape of a die. This method also fails to overcome the disadvantagesof core heat transfer to the die and slow heat dissipation from the dieduring cooling.

Based on the foregoing, it will be appreciated that there is a need fora shaping method and apparatus that provides fast and accurate transferof a heated honeycomb core to a shaping mechanism, minimizes the heatloss of the core during forming of the core, and maximizes the heat lossof the core during the cooling period. The present invention is directedto fulfilling this need.

SUMMARY OF THE INVENTION

In accordance with the present invention, a method of shaping a layer ofsettable material, such as a honeycomb core, is provided. The methodincludes: placing the core on a flexible support; translating theflexible support and core into an oven; heating the core to a desiredforming temperature; translating the support and core horizontally fromthe oven into a forming area; lowering a contoured upper die onto thecore; tensioning the flexible support; shaping the core by pressing thecore between the upper die and the tensioned flexible support so thatthe core is forced to conform to the shape of the upper die; cooling thecore to set temperature; and raising the upper die to remove thefinished formed core.

Alternatively, shaping of the core is accomplished by maintaining thecore on the flexible support and pressing the core and the supportbetween an upper and a lower die, during which time no tensioning of theflexible support is provided.

In accordance with further aspects of the present invention, anapparatus for shaping a layer of honeycomb core is provided. Theapparatus is located in a forming area adjacent an oven. The apparatusincludes an upper die capable of translating downward. The apparatusalso includes first and second tensioning assemblies, each having anelongate tray supporting a torque supply system and at least one roller.The tensioning assemblies are positioned opposite each other, orientedsuch that the roller axes of rotation are parallel. Wrapped around andextending between the rollers of the tensioning assemblies is ahorizontal flexible support for supporting a layer of settable material,such as a honeycomb core. The tensioning assemblies are mounted on guideassemblies suitable for translating the tensioning assemblies into andout of the oven. The apparatus further includes a regulation system forcoordinating torque between opposite rollers of the first and secondtensioning assemblies to ensure even tensioning of the flexible supportaround the core during pressing.

Alternatively, rather than a single upper die, the apparatus of thepresent invention includes upper and lower multi-faceted dies that arereverse images of one another. In this embodiment, the air regulationsystem eliminates tension in the flexible support when a workpiece,i.e., a layer of settable material, is compressed between the dies.

In accordance with other aspects of this invention, each guide assemblyincludes a ball screw operated by an electric motor, the ball screwbeing housed in a rail support having dual male rails mounted to itsupper surface. The guide assembly further includes a ball mountengageable with the ball screw and attachable to a lower surface of atensioning assembly; and dual female rails mounted to the tensioningassembly lower surface, the female rails being engageable with the malerails. The ball screw translates the ball mount causing the tensioningassembly to translate along the rails.

In accordance with still further aspects of this invention, thetensioning assembly is designed for use with a simple upper die havingconvex curvature in one plane and no variation in cross-section alongthe direction normal to that plane. This embodiment of the tensioningassembly includes a single roller supported on an elongate tray and anair motor for supplying torque to the roller. This embodiment includes asingle horizontal flexible support wrapped around each of the rollers ofthe first and second tensioning assemblies. During shaping, theregulation system coordinates torque between rollers of the first andsecond tensioning assemblies. This causes the flexible support tomaintain constant tension about the core during pressing, withoutimparting any sideways motion due to one roller having more torque thanthe other roller. A variation of the numbers of rollers and flexiblesupports, and their placement in the tensioning assembly, is provided.

In accordance with alternative aspects of this invention, the tensioningassembly is designed for use with a complex upper die having convexcurvature in any plane. This embodiment of the tensioning assemblyincludes a number of independent short rollers and an equal number ofair motors. The air regulation system coordinates torque between bothadjacent and opposite rollers by supplying each air motor with equalvalues of air pressure. Engaged with each short roller is a tensioningsub-assembly. Instead of a single flexible support, multiple flexiblebelts are provided. The belts are divided into equal groups, the beltsof one group being secured to components of a single tensioningsub-assembly.

In accordance with yet further aspects of this invention, the tensioningsub-assemblies include a housing having therein a pulley system toextent and retract individual flexible belts including an internal cableinterlinking a number of stationary spools to a number of rods housed intranslating brackets. The stationary spools are each attached to thehousing. The translating brackets are guided by channels in the housingand are each attached to one end of a flexible belt. During pressing,the tensioning sub-assembly allows each translating bracket and flexiblestrip to move independent of one another, while distributing appliedtension between the individual flexible belts via the interlinkinginternal cable.

In accordance with other further aspects of this invention, optionalfirst and second support rollers are provided to keep the flexiblesupport at a particular height during pressing, when using a narrowwidth simple or complex upper die. The support rollers are attached toframes supported by the floor, and are positioned directly beneath theflexible support. The exact location of the support rollers may beadjusted to accommodate a particular upper die shape.

As will be appreciated by those skilled in the art, utilization of aflexible support to transfer the core to the oven and support the coreduring forming provides a faster method of shaping the core, since thereis no need to wait for support rods to retract or to wait for a workerto properly adjust the location of a core with respect to a lower die.Using a flexible support can result in the elimination of a lower diefor some core shapes. This provides the advantages of: eliminating themismatch that occasionally occurs between two dies; lowering toolingcosts; decreasing tool setup time; and eliminating the hand-aligning ofthe core on a lower die. The flexible support adds the benefits of lessheat loss during pressing and faster heat dissipation during cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective view of an oven and a shaping apparatus formedin accordance with the present invention;

FIG. 2 is a side elevational view of the arrangement of FIG. 1;

FIG. 3 is a front elevational view of the arrangement of FIG. 1;

FIG. 4 is a top plan view of the arrangement of FIG. 1;

FIG. 5 is a side elevational view of a guide assembly formed inaccordance with the present invention;

FIG. 6 is a cross-sectional view along line 6--6 of FIG. 5;

FIG. 7 is an elevational view of a first example of a simple convexcontour upper die;

FIG. 8 is an elevational view of a second example of a simple convexcontour upper die;

FIG. 9 is an elevational view of an example of a complex convex contourupper die;

FIG. 10 is an elevational view of an example of a multi-faceted upperdie and a reverse-image lower die;

FIG. 11 is a perspective view of a first embodiment of a tensioningassembly formed in accordance with the present invention, with portionsomitted for clarity;

FIG. 12 is a perspective view of an alternative version of a firstembodiment of a tensioning assembly formed in accordance with thepresent invention;

FIG. 13 is a top plan view of a second embodiment of a tensioningassembly formed in accordance with the present invention;

FIG. 14 is a cross-sectional view along line 14--14 of FIG. 13;

FIG. 15 is a perspective view of a tensioning sub-assembly of thetensioning assembly of FIG. 13;

FIG. 16 is a perspective view of a portion of the tensioningsub-assembly of FIG. 15;

FIG. 17 is a top plan view of a portion of the tensioning sub-assemblyof FIG. 15 with the front panel removed;

FIG. 18 is a perspective view of a translating bracket of the tensioningsub-assembly of FIG. 15;

FIG. 19 is a side elevational view of the translating bracket of FIG.18; and

FIG. 20 is a perspective view of a stationary spool of the tensioningsub-assembly of FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although the following detailed description of the presently preferredembodiment of the invention is presented with reference to a workpiecein the form of a layer of honeycomb core material, it is to beunderstood that other settable materials may benefit from use of thepresent invention. Therefore, even though the present invention shapingmethod and apparatus was developed and is described herein for use withhoneycomb core, it is to be understood that the present invention mayalso be useful in the formation of other settable materials, e.g., foamsheets, thermoplastic sheets, etc.

The general method and apparatus of the present invention involvesplacing a layer of honeycomb core on a flexible support, translating theflexible support and core into an oven, and heating the core to itsproper forming temperature in the oven. Once core heating isaccomplished, the support and core are translated horizontally out ofthe oven into a forming area.

At the forming area, a contoured upper die is vertically lowered ontothe core, pushing the core and the flexible support downward. Tensioningassemblies maintain the tension of the flexible support so that the coreis pressed between the upper die and the flexible support and therebybeing forced to conform to the shape of the upper die. After pressing,the arrangement is allowed to cool. The die is then raised and thefinished, shaped core is removed. This general method and apparatus ofthe present invention is subject to a number of variations. Thevariations are discussed below. In general, the variations relate to theshape of the contoured die.

As will be readily appreciated by those skilled in the art, utilizing aflexible support to transfer a honeycomb core to an oven and support thecore during forming provides a faster method of shaping the core, sincethere is no need to wait for support rods to retract or to wait for aworker to properly adjust the location of the core with respect to alower die. In addition, using a flexible support can result inelimination of a lower die for some core shapes. This benefit isdiscussed in detail below.

FIGS. 1-4 show a shaping apparatus 22 formed in accordance with thepresent invention. Unnecessary details have been eliminated in order forthe invention to be more easily understood. Also shown in FIGS. 1-4 is aconventional oven 28 having a horizontal opening 36 for receiving itemsto be heated. The horizontal opening 36 extends around three sides ofthe oven (front side 40, left side 42, and right side 44). A formingarea 26 is defined by the area directly adjacent the oven front side 40,spanning the oven's width as shown in FIG. 1.

Still referring to FIGS. 1-4, the shaping apparatus 22 is located in theforming oven 26 and includes a die assembly 30 having a verticallytranslatable upper die 32. The die assembly is generally of a knowntype, however, variations are required for its use with the presentinvention. These variations are discussed below. The verticaltranslation of the die 32 may be accomplished using any one of a numberof known methods and power supplies, including a hydraulic press, anelectric motor, a manual mechanical pulley system, etc. The precisetranslation mechanism is not particularly important to the presentinvention. What is important is that the placement and orientation ofthe die is such that when the upper die is lowered by the verticaltranslation mechanism onto a heated core to be shaped, the die isappropriately aligned with the core.

The shaping apparatus 22 of the present invention includes first andsecond tensioning assemblies 70, 72 supported by first and second guideassemblies 50, 52, respectively, both oriented parallel to and near theoven left and right sides 42, 44, respectively. See FIG. 3. First andsecond preferred embodiments of the tensioning assembly of the presentinvention are provided and described in detail below. Each tensioningassembly 70, 72 includes an elongate tray 74 supporting a torque supplysystem, and at least one roller 76 (see FIGS. 11-14). The tensioningassemblies 70, 72 are generally rectangular in shape, having a front end78 and a rear end 80. The torque supply system may include any mechanismcapable of being back driven while engaging a roller and capable ofproviding a specific torque to the roller.

The first and second guide assemblies 50, 52 may be formed as one of anumber of conventional translation arrangements. Shown in FIGS. 5 and 6,is a ball screw arrangement where an electric motor 54 drives a ballscrew 56 housed in a rail support 58. The rear ends 80 of the first andsecond tensioning assemblies 70, 72 are engaged with the first andsecond guide assemblies 50, 52, respectively, via ball nut mounts 82capable of translating along the rotating ball screw. The first andsecond guide assemblies 50, 52 further include a pair of female linearrails 60 mounted to the underside of each tensioning assembly forengaging a pair of male linear rails 62 attached to the upper surface ofeach guide assembly rail support 58. The first and second guideassemblies of FIGS. 5 and 6 are located directly adjacent the left andright oven sides, one to a side. The upper edge of the rail support 58preferably lies just below the horizontal oven opening 36.

The electric motors 54 between the first and second guide assemblies 50,52 are synchronized to ensure that translation of the tensioningassemblies is performed in unison. Synchronization may be accomplishedusing any one of a number of known methods. A simple method is shown inFIG. 12, where a synchronization bar 160 physically extends between thefirst and second tensioning assemblies to ensure like motion.

Located between the tensioning assemblies 70, 72 is a flexible support38 having two side ends, one end is wrapped around the roller 76 of thefirst tensioning assembly 70, the other end is wrapped around the roller76 of the second tensioning assembly 72. During honeycomb core pressing,the flexible support 38 remains under the honeycomb core 24, additionalflexible support material unwinding off the rollers as required. Theflexible support may be formed of any heat resistant flexible material,the preferred material being a fine-link stainless steel wire meshcapable of withstanding at least 750° F.

The width (X-direction length) of the flexible support 38 is sufficientto span the distance between the tensioning assemblies and wrap aroundthe rollers a number of times. The depth (Z-direction length) of thesupport is at least as great as the core and die that are to be pressedtogether, but smaller than the depth of the oven. Exemplary measurementsof the flexible support are 5-feet by 12-feet, where the die is 7-feetby 4-feet, and the oven can accommodate a 4-foot by 8-foot by 3.5-inchobject. A support shelf 34 (see FIG. 3) supports the tensioning assemblyat a height (Y-direction) such that the flexible support and core mayfreely translate into and out of the oven horizontal opening 36 withoutdisruption.

The shaping apparatus 22 of the present invention further includes aregulation system for coordinating the torque produced within andbetween the torque supply systems of the first and second tensioningassemblies 70, 72. The regulation system further keeps the side ends ofthe flexible support operating in unison. If flexible supports are notoperated in unison, one tensioning assembly may react faster than theother tensioning assembly, or may be more powerful than the other one.Either situation would cause the one assembly to continuously pick upmore slack in the flexible support. During pressing, it is important tokeep even tension applied to the flexible support so that it does notshift sideways. Shifting of the flexible support could result inmalforming the honeycomb core.

The regulation system may be any one of a number of conventionalsystems, depending on the tensioning assembly configuration and, inparticular, the torque supply system selected. The specific size andtype of regulating system is not discussed herein, that information notbeing particularly important to the present invention. What is importantis that the chosen regulation system be capable of keeping even tensionbetween opposed rollers.

The shaping apparatus 22 of the present invention may also includeoptional first and second support rollers 166. See FIG. 3. The supportrollers are provided to keep the flexible support 38 at a particularheight during pressing. This is necessary when the die is narrow inwidth compared with the distance between the tensioning assemblies.Without support rollers 166, the flexible support 38 does not properlypress the core about the upper die, regardless of the applied tension.

Shown in FIGS. 1 and 3, the support rollers 166 are mounted onvertically adjustable frames 168 that are supported by the floor. Thesupport rollers and frame may be configured according to any one of anumber of methods. The simple exemplary configuration of FIGS. 1 and 3are basically weighted horses having the support rollers attached to asingle rod that forms the upper horse cross member. A more complicatedapparatus (not shown) may include support rollers attached to framescomprised of steel I-beams that are attached at their lower ends to asubfloor system of translating carriages, operated by hydraulicactuators. While the configuration selected is not particularlyimportant to the present invention, it is desirable that at least theheight of the rollers be adjustable.

Shown in FIGS. 1 and 3, the support rollers 166 and frames 168 arepositioned under the flexible support 38 such that the support roller166 is close to the underside of the flexible support. The supportrollers 166 are spaced laterally out from directly beneath the edges ofthe upper die. The axes of the first and second support rollers aregenerally parallel to the axes of rotation of the tensioning assemblyrollers. This orientation may change, however, depending on the shape ofthe die.

In operation, a workpiece in the form of a layer of honeycomb core 24 isplaced on the flexible support 38. The air motors 54 are energized,causing the two, together, to be translated by the guide assemblies 50,52 horizontally into the oven 28 via the oven opening 36. Because theoven opening extends around the oven front side 40 through both the leftand right sides 42, 44, the flexible support 38 is smoothly translatedinto the oven without any portion of the core, or the flexible support,touching the oven. A portion of the support and the tension assembliesextend horizontally out from the sides of the oven opening.

Next, the core 24 is heated to its forming temperature. Afterwards, thecore and support are translated horizontally out of the oven 28 backinto the forming area 26. Then the upper die 32 is lowered onto thecore, the upper die pushing the core into the flexible support. Thefirst and second tensioning assemblies maintain the tension on theflexible support so that the core is forced to conform to the shape ofthe upper die. After the core cools to its set temperature, the die israised and the shaping process is complete.

Further details of the present invention depend on the size and shape ofthe upper die. Generally, dies may be divided into three differenttypes: simple convex dies having only convex curvature in only the X-Yplane and no variation in the Z-direction; complex convex dies havingconvex curvature in any plane; and multifaceted dies having eitherconvex or concave curves, or both, in any plane. Examples of simpleconvex dies are shown in FIGS. 7 and 8. In FIG. 7, the die 32a is shapedsimilar to a side portion of a cylinder--the curvature of the die lyingin the X-Y plane and the cross-sectional shape of the die experiencingno variation in the Z-direction, while in FIG. 8, the convex curvatureof the die 32b is more complex, though still occurring in only the X-Yplane. The cross-sectional shape remains constant in the Z-direction.

An example of a complex convex die is shown in FIG. 9, where the die 32cis shaped similar to a half cone--the curvature of the die lying in theX-Y plane and the Z-direction shape varying linearly. An example ofmulti-faceted dies is shown in FIG. 10. Rather than a single upper die,the multi-faceted die includes upper and lower dies 33a and 33b that arereverse-images of one another. Each multi-faceted die may include bothconvex and concave curves in any plane.

The type of die used to form a core will determine the tensioning methodused and whether an additional, lower die 33b is required. Various typesof tensioning mechanisms and their components, all formed in accordancewith this invention, are illustrated in FIGS. 11-20 and described below.Simple convex honeycomb forms may use any of the hereinafter describedtensioning assemblies with only an upper die. Complex honeycomb formsmay be limited to the more complex tensioning assemblies, but with onlyan upper die. Multi-faceted honeycomb forms require the more complextensioning assemblies, with a lower die as well as an upper die.

The tensioning assemblies 70, 72 formed in accordance with the presentinvention, and shown in FIG. 11, each include a single roller 76 thatextends substantially the entire longitudinal length of the tensioningassembly. The roller 76 is supported in the tensioning assembly elongatetray 74 using conventional methods. One end of the flexible support iswrapped around the roller of each tensioning assembly 70, 72 a fewtimes, preferably such that support 38 rolls off the rollers 76 from thetop, rather than the bottom of the rollers. The rollers may be formed ofany sufficiently rigid material. In actual prototypes of the invention,the chosen materials were titanium or aluminum rollers having a diameterof 2-inches to 3-inches and a length of approximately 50-inches to65-inches.

The torque supply system includes a reversible air motor 84 attacheddirectly to one or both ends of each roller. FIG. 11 shows a single airmotor 84 attached to the front end of the roller 76. The air motor 84 isenergized by a suitable pressurized air source. Each air motor iscapable of sustaining a given torque on its respective roller.

Other torque supply systems may be used instead of an air motor system(e.g., a mechanical spring system, a hydraulic system, an electric motorsystem, etc.) Whatever system is selected, it must be capable ofpreventing rotation of the rollers during oven transfer and be capableof being back driven under tensioning during pressing in order tosustain a specific tension on the core while still allowing the rollersto partially unwind.

The actual value of the torque provided by a given torque supply systemwill be dependent upon the requirements of a particular application. Anexample torque supply system may utilize air motors capable of supplying20 ft-lbs torque using a constant supply of air pressure at 90 psig.

As will be appreciated by those skilled in the art, the embodiment ofthe tensioning assembly shown in FIG. 11 is suitable for shaping ahoneycomb core about a simple convex contour upper die. Because there isno variation in the die shape along the Z-direction, the support neatlywraps around the die, equally compressing the core against the die atall core locations. As will also be appreciated by those skilled in theart, such a method and apparatus requires only an upper die. No lowerdie is required. The benefits of eliminating the lower die include:elimination of any mismatch (which occurs occasionally) between twodies; lower tooling costs; and faster tool setup time. Additionally,because the flexible support is heated with the core, less heat is lostthan when a heated core is pressed against a cold lower die duringpressing. After pressing, the flexible support dissipates heat morequickly than a lower die. (The period of time required for forming isgenerally less than the period of time required by the flexible supportto switch from acting as a heat source to a heat sink.)

FIG. 12 shows a variation of the embodiment of the tensioning assemblyshown in FIG. 11. The embodiment shown in FIG. 12 includes three rollers88 and three reversible air motors 87 per tensioning assembly. Therollers 88 shown in FIG. 12 are similar to the rollers 76 shown in FIG.11, only shorter in axial length. The rollers 88 of FIG. 12 are arrangedparallel to one another, in a common horizontal plane. The singleshaping apparatus flexible support 36 is replaced by three smaller-widthflexible supports 86 positioned horizontally side-by-side. The side endof each support is wrapped about a single roller 88. Each roller 88 isrotated by an associated air motor 87. This tensioning assemblyvariation is most useful for upper dies with gentle complex convexcontours. Using multiple flexible supports with such dies helps compressthe core to the die without introducing significant complexity into theapparatus of the invention.

Other variations of the tensioning assemblies shown in FIGS. 11 and 12are possible and will vary according to the die contour and the pressingforce required. In general, such variations may require a greater orlesser number of flexible supports. The preferred arrangement isalternating rollers in outboard relation, i.e., a first roller is placedat one location, a second roller is placed closer in, a third is placedin axial alignment with the first roller, a fourth is placed in axialalignment with the second roller, etc. In this way, there is sufficientroom for all air motors.

The air regulation or control system used with the tensioning assembliesillustrated in FIGS. 11 and 12 should be capable of coordinating thepressure and torque between adjacent and opposed air motors of the firstand second tensioning assemblies such that portions of the core beingshaped receive the same pressing force. This is most easily accomplishedby using a constant pressure source for each air motor, the air pressureamounts between air motors being the same.

More specifically, during pressing, i.e., when the upper die is loweredonto the honeycomb core 24, the air motors 84 (or 87) provide a constanttension to the flexible support 38 (or 86) while the flexible support isunwinding from the rollers due to the core being pressed downwardagainst the flexible support by the upper die 32. A simple regulationsystem uses constant (and equal) shop pressure sources attached to eachair motor.

FIGS. 13-20 illustrate a more complex embodiment of a tensioningassembly formed according to the present invention. Each tensioningassembly includes a number of independent short rollers 92 (six rollersare shown in FIG. 13) positioned end-to-end along nearly the entirelongitudinal length of the elongate tray 74. The short rollers 92 aremounted for independent rotation on a single shaft 94.

The tensioning assembly shown in FIG. 13 also includes a number offlexible belts 96. The belts 96 are placed horizontally side-by-side inthe X-Z plane. The belts 96 may be formed of the same material as theflexible support 38 described above, only much narrower in width. Thebelts 96 support the core 24 during heating and force the core againstthe upper die 32 during pressing. The end of each of the belts 96 isattached to a tensioning sub-assembly 90 instead of being attacheddirectly to the short rollers 92. The manner of attachment illustratedin FIG. 18 is described in detail below. As described next, thetensioning assemblies are attached to the short rollers 92.

Referring to FIGS. 15 and 16, the tensioning sub-assemblies 90 include agenerally square housing 98 having a roller cable 100 (or similarlystrong flexible material) wrapped around two roller cable spools 176attached to the inside surface of a housing back panel 134 near an uppersurface 102 of the housing. More specifically, the roller cable 100extends from the upper edge of the housing to have each of the cable'stwo ends wrap around a common short roller 92, as shown in FIG. 13. Alsoshown in FIG. 13 are optional ring-like roller cable guides 118 mountedon the short rollers to help guide the roller cable 100 around the shortroller 92.

The torque supply system of the tensioning assemblies shown in FIGS.13-20 includes a number of air motors 108, one for each short roller 92.The air motors 108 of FIG. 13 are mounted in the tray 74 in a staggeredformation in order to optimize tray space usage. The staggering shown inFIG. 13 is accomplished by placing one air motor close to its shortroller, the next far from its short roller, the third close to its shortroller, etc. Alternatively, or in addition, the air motors 108 may bevertically staggered to save space as well.

As shown in FIGS. 13 and 14, a sprocket chain mechanism is used tocouple the air motor 108 to their related short rollers 92. Morespecifically, a drive sprocket 112 is mounted on the shaft 110 of eachair motor 108. A drive chain 116 is wrapped around each of the drivesprockets 112 and a roller sprocket 112 that girdles the centerperiphery of an associated short roller 92. See FIG. 14. Attached to thetray 74 are six stops 120, shown in FIGS. 13 and 14. The stops 120function to prohibit the roller cables 100 from winding so far onto theshort rollers that they cause the tensioning sub-assemblies to come intocontact with the roller sprocket 114, chain loop 116, or belt guides118. The stops 120 therefore protect both the tensioning sub-assembly 90and the tray components.

Also shown in FIGS. 13 and 14 are some of the components of theregulation system. In particular, a common air pressure supply line 122having individual branches 124 to each air motor 108 is provided. Thecommon line is attached to a supply of air pressure. The air pressuresupplied to each air motor is held to a constant in order to equalizethe tensioning capability of each of the air motors on their associatedrollers. Any one of a number of known systems may be used for theregulation system, the precise configuration not being particularlyimportant to the present invention.

The details of each tensioning sub-assembly are shown in FIGS. 15-20. InFIG. 15, each housing 98 is shown as including a lower side 126 andfirst and second sides 128, 130. The housing 98 is formed from theattachment of a square front panel 132 to a square back panel 134, withmultiple elongate dividers 136 placed therebetween. See FIG. 16. Thepreferred panel material is aluminum. This attachment may be formedusing any one of a number of known methods. Small transverse screws 138are shown in FIG. 15. The roller cable spools 176 are attached betweenthe front and back panels near the upper edge 102. The axial orientationof the spools 176 is transverse to the plane of the panels.

The elongate direction of the dividers 136 is oriented parallel to thehousing side edges 128, 130. The dividers 136 are shorter in length thanthe distance between the housing upper surface 102 and lower side 126.The dividers are placed equa-distance from each other to form channelsextending from the housing lower edge to nearly the top edge of thepanels. At the lower edge 126 of the housing 98 is a bracket stop 111spanning the width of the housing 98.

The number of dividers required will depend upon the number of channelsrequired, which in turn corresponds with the number of flexible belts 96attached to each tensioning sub-assembly 90. Five dividers are needed toform four channels for a tensioning sub-assembly accommodating fourflexible belts. The numbers given here are exemplary and not to beconstrued as limiting. The present invention encompasses using othernumbers depending on the needs of a particular application.

The dividers that are located inward of the front and back panel sideedges, each have a stationary spool 142 (shown in FIGS. 17 and 20)secured near their upper ends, between the front and back panels, theaxis of rotation of the spools 142 being transverse to the plane of thefront and back panels 132, 134. The stationary spools 142 are locatednear the upper housing surface 102 and are capable of rotation in eitherdirection. The spools 142 are preferably formed of stainless steel.

Referring to FIG. 17, a translating bracket 144 is located in eachchannel. Each bracket 144 is sized to slide easily within its channel,loosely contacting the dividers and the inner surfaces of the front andback panels. Referring to FIG. 16, the back panel 134 may optionallyinclude one or more lubrication access holes 140 for lubricating thetranslating brackets. The translating brackets 144 are preferably formedof phenolic.

As shown in FIG. 19, each translating bracket includes an upper edge 148lying closest to the housing upper surface, a lower edge 150 oppositethe upper edge, and an internal rod 146 located near the upper edge 148.The internal rod is mounted to rotate in either direction. The axis ofrotation of the internal rod 146 is generally parallel to the axis ofrotation of the stationary spools 142. One end of a flexible belt 96 isattached to a translating bracket 144 through the bracket's lower edge150. This attachment may be accomplished in one of a number of knownways. Shown in FIG. 19 are transverse bolts 152.

Referring to FIGS. 15 and 17-19, each translating bracket 144 furtherincludes a guide 156 secured to the surface of the bracket that isadjacent the front panel 132. The front panel 132 includes a number ofslots 154 for accommodating the guides 156, one translating bracketguide extending into each slot. The slots are sized to correspond to thelocation of the guide when the bracket is in uppermost region of itschannel (i.e., retracted position) to the location of the guides whenthe bracket is in the lowermost region of its channel (i.e., extendedposition). The slots guide the bracket guides 156, and hence thebrackets and flexible belts, in going between their extended andretracted positions. The housing bracket stop 111 further helps tocontain the translating brackets 144 in their respective channels.

The housing 98 further includes a single internal cable 158 having twoends. One end is secured to the housing near one upper edge comer 162,and the other end is secured to the housing near the other upper edgecomer 164. See FIG. 17. Between the two upper comers 162, 164, theinternal cable 158 is connected between the translating bracket internalrods 146 and the stationary spools 142, in alternating fashion, as shownin FIG. 17. As will be appreciated by those skilled in the art, thetensioning sub-assembly is basically a pulley device where the overalltension provided by any one roller is divided equally among its flexiblebelts. Thus, slack occasioned by a belt covering a small upper die crosssection distance is consumed by belts experiencing less slack.

During the pressing operation using a tensioning assembly of the typeshown in FIGS. 13-20, when the upper die is lowered onto the honeycombcore 24, the core and flexible belts begin to unwind off the shortrollers via the roller cables 100. During this time, the air regulationsystem ensures that the air motors provide equal tension betweentensioning sub-assemblies through each air motor's respective roller.The tensioning sub-assemblies themselves further distribute tensioningequally among their flexible belts by extending and retracting thebrackets in the channels. The internal cable running between thetranslating brackets ensures that equal force is applied by eachflexible belt to the honeycomb core being shaped.

As will be appreciated by those skilled in the art, the embodiment ofthe tensioning assembly shown in FIGS. 13-20 is ideally suited forshaping a honeycomb core about a complex convex contour upper die. Theuse of multiple flexible belts 96, tensioning sub-assemblies 90, and aregulation system accomplishes an even distribution of tension betweenall flexible belts. Therefore, variation in the die shape along theZ-direction is accommodated because the core receives the same pressingforce at all locations. Such a tensioning assembly requires only anupper die. As discussed above, elimination of the lower die is asignificant improvement over prior art methods and apparatus.

For multi-faceted dies, an alternative method is used. In this method,shaping of the core is accomplished by maintaining the core on theflexible support and pressing the core and the support, together,between the upper and a lower die. The lower die is necessary formulti-faceted die curve due to its surface shape inflection variations.

To accomplish this method, the apparatus of the present invention islikewise altered. In particular, both an upper and lower die areincluded, and the regulation system is set to eliminate tension in theflexible support during pressing. The tensioning assembly providestension only when the core is being heated and transferred to and fromthe oven. During core pressing, there is no tension on the flexiblesupport.

The lower die is positioned below the core, adjacent the flexiblesupport: the upper die is positioned above the core, adjacent the core'supper surface. The lower die is the reverse-image shape of the upperdie. This embodiment of the present invention is useful mainly forgently curved honeycomb core products. Tight corners tend to cause thesupport to bunch up between the dies. The remaining aspects in thisalternative method and apparatus are the same as described above,including the availability of using any of the various embodiments ofthe tensioning assemblies.

Although the alternative method and apparatus embodiment offers nobenefits resulting from the elimination of a die, it is still animprovement over current methods and apparatus. Utilizing a flexiblesupport to transfer the core to the oven and support the core duringforming provides a faster method of shaping the core, since there is noneed to wait for support rods to retract or to wait for a worker toproperly adjust the core on the lower die. In addition, the flexiblesupport provide a degree of insulation between the core and the coldlower die, thus raising the initial compression temperature and helpingto maintaining an increased temperature during compression.

While the preferred embodiment of the invention has been illustrated anddescribed, it will be appreciated that various changes can be madetherein without departing from the spirit and scope of the invention.One variation is to utilize just the tensioning assembly and die(s)without providing for translation into an adjacent oven via guideassemblies. Such an embodiment is not preferred, however, since itrequires handling of the core between heating and pressing which cancause core temperature loss, and misalignments.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A method of shaping alayer of settable material, the steps comprising:(a) placing the layerof settable material on a flexible support; (b) translating the flexiblesupport with settable material to a heat source; (c) heating thesettable material to a desired forming temperature; (d) translating theflexible support with settable material from the heat source to aforming area; and (e) pressing the settable material using a die havinga particular shape, the pressing occurring between the die and theflexible support by tensioning the flexible support so that the settablematerial is forced to conform to the shape of the die.
 2. The method ofshaping according to claim 1, wherein pressing further includescoordinating tension between portions of the flexible support so that apressing force is substantially uniform over the entire layer ofsettable material.
 3. The method of shaping according to claim 1,wherein the die is a convex contour die.
 4. The method of shapingaccording to claim 1, wherein the heat source is positioned adjacent theforming area and wherein pressing occurs immediately after translatingthe flexible support with settable material from the heat source.
 5. Theshaping method of claim 1, further comprising:(a) providing first andsecond tensioning assemblies, each including at least one roller and atleast one torque supply system for rotating the at least one roller; theflexible support having one end rotatably connected to the at least oneroller of the first tensioning assembly and an opposite end rotatablyconnected to the at least one roller of the second tensioning assembly;and (b) providing a regulation system operably engaged with the at leastone torque supply systems of both the first and second tensioningassemblies, the regulation system equalizing tension between the ends ofthe flexible support and keeping the torque supply systems operating inunison.
 6. The shaping method according to claim 5, wherein each torquesupply system includes at least one air motor in communication with itsrespective roller and capable of sustaining a constant torque on theroller and wherein the regulation system includes a constant airpressure source attached to the air motors.
 7. The shaping methodaccording to claim 1, wherein translating the flexible support includesusing a guide assembly attached to the first and second tensioningassemblies.
 8. The shaping method according to claim 1, wherein the dieis a male die and the flexible support includes at least two flexiblebelts positioned side-by-side and attached at their first ends to afirst tensioning sub-assembly and attached at their second ends to asecond tensioning sub-assembly, the first and second tensioningsub-assemblies being rotationally connected to opposed rollers, theopposed rollers providing tensioning of the flexible support and thefirst and second tensioning sub-assemblies equalizing tension betweenthe at least two flexible belts.
 9. The shaping method according toclaim 8, wherein each tensioning sub-assembly comprises:(a) atranslating bracket attached to each flexible belt end; (b) a housinghaving adjacent channels, each channel for receiving and containing onetranslating bracket with flexible belt end; and (c) a cableinterconnecting the translating brackets, whereby tension is equalizedbetween the flexible belts via the cable acting on the translatingbrackets.
 10. A method of shaping a layer of settable material, thesteps comprising:(a) placing the layer of settable material on a heatresistant flexible support positioned in a forming area; (b) translatingthe flexible support with settable material into a heat sourcepositioned adjacent to the forming area; (c) heating the settablematerial to a desired forming temperature in the heat source; (d)translating the flexible support with settable material from the heatsource into the forming area; and (e) pressing the settable material andthe flexible support between an upper die and a lower die.
 11. Themethod of shaping according to claim 10, wherein the flexible supportincludes a number of flexible belts disposed side-by-side to each other.12. The method of shaping according to claim 10, wherein the flexiblesupport is attached to a guide assembly and wherein translating theflexible support with settable material into and from the heat sourceincludes actuating the guide assemble.
 13. The method of shapingaccording to claim 10, wherein the flexible support is attached betweenfirst and second tensioning assemblies capable of applying tension tothe flexible support and wherein translating the flexible support withsettable material into and from the heat source includes actuating atensioning assembly to cause the flexible support to remain in asubstantially horizontal orientation.
 14. The method of shapingaccording to claim 13, further including actuating the tensioningassembly to eliminate tension in the flexible support during pressing.15. The shaping method according to claim 10, wherein:(a) the flexiblesupport is attached between first and second tensioning assembliescapable of applying tension to the flexible support, each tensioningassembly comprising a number of rollers mounted end-to-end on a shaftand a number of torque supply systems, one torque supply system for eachroller; (b) the flexible support including at least two flexible beltspositioned side-by-side and attached at their first ends to a firsttensioning sub-assembly and attached at their second ends to a secondtensioning sub-assembly, the first tensioning sub-assembly beingrotationally connected to a roller of the first tensioning assembly, thesecond tensioning sub-assembly being rotationally connected to a rollerof the second tensioning assembly, the first and second tensioningsub-assemblies equalizing tension between the at least two flexiblebelts; and (c) a regulation system engaged with the torque supplysystems of both the first and second tensioning assemblies, theregulation system maintaining a desired amount of torque between eachtorque supply system and equalizing tension between tensioningsub-assemblies.
 16. The shaping method according to claim 15, whereineach torque supply system includes at least one rotary actuator incommunication with its respective roller and capable of sustaining aconstant torque thereon.